1. Field of the Invention
This invention relates to disk drive suspensions and, more particularly, to load beams for disk drive suspensions. The invention suspensions utilize microactuation by a piezoelectric crystal to shift the load beam distal end relative to a disk to be read.
2. Related Art
Load beams are used to carry sliders containing read/write heads adjacent spinning disks. The load beam has a base portion anchored to an actuator arm that pivotally shifts the load beam and its associated slider angularly to move between tracks on the disk. The mass and inertia of conventional actuators means it requires considerable power to operate them.
It is an object of the present invention to provide an improved suspension. It is a further object to provide a load beam of novel design. It is a further object to provide for the actuation of a suspension load beam with microactuators acting against a beam spring portion having an expansion and contraction capability. It is a further object to utilize piezoelectric crystals acting between the load beam base potion and the beam portion across the spring portion under voltages of less than about 40 volts and achieving displacements of the load beam carried slider of about 2 micrometers in the Y-axis. It is a still further object to provide a load beam having specially conformed spring elements disposed from vertically to laterally the load beam to support the beam portion from the base portion but also to readily allow changes in dimension of the spring portion through the decrease or increase in an arcuate section of the spring elements.
The invention accordingly provides a disk drive suspension comprising a load beam extended along a longitudinal axis, the load beam having a base portion, a beam portion adapted to carry a slider in operating proximity to a disk, a spring portion connecting the base portion to the beam portion, and an electrodynamic microactuator coupled between the base and beam portions, the spring portion being elongatable and contractable in response to elongation or contraction of the microactuator, typically by the incorporation of arcuate sections along the length of the spring portion that increase or decrease their radius of curvature in response to elongation or contraction, respectively, of the microactuator.
In a particular aspect, the invention provides a disk drive suspension comprising a load beam having a base portion, a spring portion and a beam portion adapted to carry a slider in operating proximity to a disk, a dimensionally variable electrodynamic microactuator coupled to the base portion and the beam portion and across the spring portion in beam portion displacing shifting relation to the base portion over a distance that is a function of an applied voltage to the microactuator and the resistance of the spring portion to changes in dimension, the spring portion comprising a plurality of spring elements with local arcuate sections providing low resistance change in spring portion dimensions, whereby the beam portion is displaced an increased distance at a given applied voltage.
In this and like embodiments, typically, the suspension includes left and right hand microactuators acting on the beam portion in displacing relation, the microactuator comprises a piezoelectric crystal, and the applied voltage is less than about 40 volts, and the beam portion is displaced up to 2 micrometers in the Y-axis.
In a further embodiment, the invention provides a disk drive suspension comprising a load beam having a base portion, a spring portion and a beam portion adapted to carry a slider in operating proximity to a disk, a dimensionally variable piezoelectric crystal microactuator coupled to the base portion and the beam portion and across the spring portion in beam portion displacing relation to the base portion over a distance that is a function of an applied voltage to the microactuator and the resistance of the spring portion to changes in dimension, the spring portion comprising a plurality of spring elements with local arcuate sections providing low resistance change in spring portion dimensions, whereby the beam portion is displaced an increased distance shifting at a given applied voltage.
In this and like embodiments, typically, each spring element comprises a unitary part of a common web with the beam base portion and the beam portion, the spring element having fore and aft tabs connected to the beam and base portions respectively and an arcuate section connected to the fore and aft tabs in beam supporting relation relative to the base, the spring elements extending normal to said load beam and being generally parallel, separated and of like curvature in their arcuate sections, the spring portion comprises left and right spring elements, each spring element having an arcuate section intermediate the spring element ends, the arcuate sections tending to flatten to a greater radius curve when the spring portion element is elongated by action of the microactuator and to curl to a lesser radius curve when the spring portion element is contracted by action of the microactuator and individually for each spring element; the spring portion comprises left, right and center spring elements, each spring element having an arcuate section intermediate the spring element ends, the arcuate sections tending to flatten to a greater radius curve when the spring portion element is elongated by action of the microactuator and to curl to a lesser radius curve when the spring portion element is contracted by action of the microactuator and individually for each spring element; the spring element comprises a unitary part of a common web with the beam base portion and the beam beam portion, the spring element having fore and aft tabs connected to the beam and base portions respectively and an arcuate section connected to the fore and aft tabs in beam supporting relation relative to the base, the spring elements being generally parallel, separated and of like curvature in their arcuate sections. In a further embodiment, typically, each spring element comprises a unitary part of a common web with the beam base portion and the beam portion, the spring element having fore and aft tabs connected to the beam and base portions respectively and an arcuate section connected to the fore and aft tabs in beam supporting relation relative to the base, the spring elements extending oppositely from the load beam and open to each other in a common plane including the load beam base and rigid portion, the arcuate sections being of like curvature in their arcuate sections, and the spring portion comprises left and right spring elements, each said spring element having an arcuate section intermediate the spring element ends, the arcuate sections tending to flatten to a greater radius curve when the spring portion element is elongated by action of the microactuator and to curl to a lesser radius curve when the spring portion element is contracted by action of the microactuator and individually for each spring element.
In each of the foregoing embodiments, typically, the microactuator comprises right and left piezoelectric crystals coupled between the base and beam portions inboard of the left and right spring elements; the applied voltage is less than 40 volts, the piezoelectric crystals are about 0.0075 inch in thickness, and the beam portion is displaced shifted up to 2 micrometers in the Y-axis.